State-of-the-art of the high dose influenza vaccine in Spain.

High-dose (HD) influenza vaccines have demonstrated robust effectiveness in preventing severe influenza-related outcomes, including pneumonia, cardiorespiratory complications, and mortality, with evidence from randomized clinical trials, meta-analyses, and real-world studies consistently showing superiority over standard-dose (SD) vaccines and supporting international recommendations for adults aged ≥60 years. This is increasingly relevant in the context of global aging and immunosenescence, which weakens vaccine-induced immune responses and heightens biological frailty, functional decline, and the risk of severe complications in older adults, especially those with comorbidities. The objective of this work is to describe the introduction, uptake, and current use of HD influenza vaccines in Spain and to summarize the evidence supporting their broader adoption in adults ≥60 years of age. Methods include a narrative synthesis of clinical evidence and an analysis of vaccination strategies implemented across Spanish autonomous communities since the introduction of HD vaccines during the COVID-19 pandemic. Available evidence supports extending HD vaccine use as a population-based strategy to enhance protection and promote equitable access. The results show that the incorporation of HD influenza vaccines marked a significant shift in national vaccination strategies, with heterogeneous uptake across regions: while some prioritized institutionalized or dependent populations, others implemented mixed approaches that also included community-dwelling adults aged ≥60 years. In conclusion, a clear trend toward wider adoption is emerging, with an increasing number of autonomous communities incorporating HD vaccines into their programs and progressively lowering the recommended age threshold, in alignment with international guidance and the biological rationale for strengthened protection in older adults.